Switching regulator is a vitally important device. Switching regulators are building blocks used extensively in power systems, industry, motor, communication, networks, digital systems, consumer electronics, computers, and any other fields that high efficient voltage regulating functions.
Switching regulators (i.e., DC-TO-DC converters) can provide output voltages which can be less than, greater than, or of opposite polarity to the input voltage. Prior Art FIG. 1 illustrates a basic architecture of a conventional switching regulator 100. The conventional switching regulator 100 basically consists of an oscillator, a reference circuit 102, an error amplifier, a modulator including a comparator, resistors, and a control logic circuit. Control technique of switching regulators has typically used two modulators: a pulse-width modulator and a pulse-frequency modulator. The output DC level is sensed through the feedback loop including two resistors. An error amplifier compares two input voltages: the sampled output voltage and the reference voltage. The output of the error amplifier is compared against a periodic ramp generated by the saw tooth oscillator. The pulse-width modulator output passes through the control logic to the power switch. The feedback system regulates the current transfer to maintain a constant output voltage within the load limits. In other words, it insures that the output voltage level reaches the equilibrium. However, it takes a vast amount of time until the output voltage level reaches the equilibrium from an initial condition after the system starts. When the output voltage level reaches the equilibrium, VF is equal to VREF, as shown in Prior Art FIG. 1.
Since a power supply of a core processor is connected to one of the outputs of switching regulators in most system applications, even the core processor should stand by to operate until it receives the expected output voltage level from the switching regulator. Therefore, power and time are consumed until the switching regulator's output voltage level reaches the equilibrium. In most switching regulator applications, it is highly desirable to control all of the switching regulators on a chip to start differently according to power sequence such as core-up-first and core-down-last or enable all of the switching regulators' output voltage levels to reach the equilibrium immediately for much higher power efficiency. In addition, the conventional switching regulator 100 has taken a long time to be simulated and verified before they are fabricated since the simulation time in designing the conventional switching regulator is absolutely proportional to time to require the switching regulator's output voltage level to reach the equilibrium. Hence, this long simulation adds additional cost and serious bottleneck to design time-to-market. In other words, the slow start-up of the switching regulator increases design simulation time. For these reasons, the conventional switching regulator 100 of Prior Art FIG. 1 is very inefficient to implement in system-on-chip (SOC) or integrated circuit (IC).
Thus, what is needed is a fast starting-up switching regulator that can be highly efficiently implemented with a drastic improvement in start-up time controllability, performance, time-to-market, power consumption, power and time management, efficiency, cost, and design time. The present invention satisfies these needs by providing five embodiments.